Programmable Relay Control Module (PRCM) Caterpillar

Illustration 1	g00715369
System schematic of the PRCM, relay driver module and relay boards

The RDM communicates with the PRCM by a serial data link. When the data link malfunctions, the "R1" output (terminal 2 of the RDM) will flash at a rate of .5 Hz. Relays "R2" through "R9" will maintain the present state or relays "R2" through "R9" will default to the OFF position. This is controlled by a jumper between terminal 6 and terminal 7 of the RDM. If the jumper is NOT present and the serial data link has a failure, relays "R2" through "R9" will remain in the present state. If the jumper is present, relays "R2" through "R9" will default to the OFF position.

Note: The maximum number of the RDM or the Customer Interface Module (CIM) that may be connected to the serial data link is equal to two. The maximum distance between a module and the PRCM is 305 m (1000 ft). The LED indicators for the RDM may start flashing if the specifications for the maximum distances are not met. The PRCM may display a CID 0333 diagnostic code. If the setup is not in compliance with the specifications, reduce the number of modules and/or shorten the distance to the modules.

Note: The following procedure can create numerous related diagnostic codes. When all harnesses are reconnected, the related diagnostic codes will be shown as being not active. Clear all related diagnostic codes after this procedure is completed.

The possible cause of a CID 0333 FMI 04 is a short to "B-" and the wire connected to contact 35 of the PRCM.

The PRCM treats a CID 0333 FMI 04 as an alarm. Clear the diagnostic code from the fault log after the troubleshooting procedure is completed.

Note: Check the terminal strips on the subpanel for a short when a CID 0333 FMI 04 is active on the upper display and no alarm module is installed. Perform the check from the signal wire to "B+". Also, check the customer connection box for a short from the alarm data signal wire to "B+".

Test Step 1. CHECK IF THE DIAGNOSTIC CODE IS ACTIVE

1. Turn the engine control switch (ECS) to the OFF/RESET position and then turn the ECS to the STOP position.

2. Press the "MODE" button.

   Note: The "MODE" button is accessed from the diagnostic code viewing/clearing menu.

3. Observe the upper display for a CID 0333 FMI 04. The diagnostic code is active if the upper display shows a CID 0333 FMI 04.

4. If the diagnostic code is not showing, enter the service mode and view the fault log. Check the upper display if the diagnostic code is active.

   Note: The PRCM must be set up properly in order to view the fault log. See Systems Operation, "Setpoint Viewing and Programming".

Expected Result:

A CID 0333 FMI 04 is active.

Results:

• OK - A CID 0333 FMI 04 is active. Proceed to test step 2.

• CODE NOT ACTIVE - NOT LOGGED - A CID 0333 FMI 04 has NOT occurred. The diagnostic code is NOT active. The PRCM must not have been setup in order to view logged diagnostics during the initial setup.

  Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors. See Testing and Adjusting, "Electrical Connector - Inspect".

  Stop.

• CODE NOT ACTIVE BUT LOGGED - The diagnostic code is NOT active. The diagnostic code is logged in the fault log. The initial diagnostic was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal operation. Stop.

Test Step 2. CHECK THE PRCM.

1. Disconnect the cable on the negative terminal of the battery or open the optional battery disconnect switch.

2. Disconnect the data link wire from contact 35 of the PRCM.

3. Reconnect the cable on the negative terminal of the battery or close the optional battery disconnect switch.

4. Turn the engine control switch (ECS) to the STOP position.

Expected Result:

A CID 0333 FMI 04 is NOT active.

Results:

• OK - A CID 0333 FMI 04 is NOT active. Proceed to test step 3.

• NOT OK - A CID 0333 FMI 04 is active. The PRCM may have failed.

  Repair: It is unlikely that the PRCM has failed. Exit this procedure and perform this procedure again. Recheck the status of the diagnostic code. Replace the PRCM if the cause of the diagnostic code is not found. See Testing and Adjusting, "Programmable Relay Control Module - Replace".

  Stop.

Test Step 3. CHECK THE RDM AND DATA LINK WIRE.

1. The data link wire remains disconnected from the PRCM.

2. Disconnect the cable on the negative terminal of the battery or open the optional battery disconnect switch.

3. Disconnect the data link wire from terminal 4 of the relay driver module.

4. Measure the resistance from the data link wire to the Battery negative on the PRCM.

Expected Result:

The resistance should be greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. Proceed to test step 4.

• NOT OK - The resistance is greater than 5000 ohms. The data link wiring has failed.

  Repair: Repair the harness or replace the harness.

  Stop.

Test Step 4. CHECK THE RDM.

1. The cable on the negative terminal of the battery remains disconnected or the optional battery disconnect switch is open.

2. The data link wire remains disconnected.

3. Measure the resistance from terminal 4 of the relay driver module to the battery negative.

Expected Result:

The resistance should be greater than 5000 ohms.

Results:

• OK - The resistance that is measured is greater than 5000 ohms. The problem may be intermittent.

  Repair: Examine the wiring between the PRCM and the RDM for nicks, abrasions, or other damage.

  Stop.

• NOT OK - The resistance is NOT greater than 5000 ohms. The RDM has failed.

  Repair: Replace the RDM.

  Stop.